Electrical interconnection system

ABSTRACT

Embodiments related to electrical connectors including superelastic components are described. The high elastic limit of superelastic materials compared to conventional connector materials may allow for designs which provide reliable connections and high frequency operation. Superelastic components also may enable connector designs with higher densities of connections. In some embodiments, a connector includes one or more superelastic elongated members forming the mating contacts of the connector. The superelastic elongated members deform within one or more conductive receptacles to generate a suitable contact force. The conductive receptacles may include a plurality of protrusions arranged to deflect the superelastic elongated members during mating. A superelastic component may also be provided in a receiving portion of a connector, and may form a portion of a conductive receptacle.

RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.15/985,158, filed on May 21, 2018, entitled “ELECTRICAL INTERCONNECTIONSYSTEM,” which is a divisional of U.S. application Ser. No. 15/098,498,filed on Apr. 14, 2016, now U.S. Pat. No. 9,991,617, entitled“ELECTRICAL INTERCONNECTION SYSTEM,” which claims the benefit of andpriority under 35 U.S.C. § 119(e) to U.S. Provisional Patent ApplicationSer. No. 62/147,450, filed on Apr. 14, 2015, entitled “ELECTRICALCONNECTORS.” The entire contents of these applications are incorporatedherein by reference in their entirety for all purposes.

FIELD

Disclosed embodiments are related to interconnection systems, such asthose including electrical connectors, used to interconnect electronicassemblies.

DISCUSSION OF THE RELATED ART

Electrical connectors are used in many electronic systems. It isgenerally easier and more cost effective to manufacture a system asseparate electronic assemblies, such as printed circuit boards (“PCBs”),which may be joined together with electrical connectors. A knownarrangement for joining several printed circuit boards is to have oneprinted circuit board serve as a backplane. Other printed circuitboards, called “daughterboards” or “daughtercards,” may be connectedthrough the backplane.

A known backplane is a printed circuit board onto which many connectorsmay be mounted. Conducting traces in the backplane may be electricallyconnected to signal conductors in the connectors so that signals may berouted between the connectors. Daughtercards may also have connectorsmounted thereon. The connectors mounted on a daughtercard may be pluggedinto the connectors mounted on the backplane. In this way, signals maybe routed among the daughtercards through the backplane. Thedaughtercards may plug into the backplane at a right angle. Theconnectors used for these applications may therefore include a rightangle bend and are often called “right angle connectors.”

Connectors may also be used in other configurations for interconnectingprinted circuit boards and for interconnecting other types of devices,such as cables, to printed circuit boards. Sometimes, one or moresmaller printed circuit boards may be connected to another largerprinted circuit board. In such a configuration, the larger printedcircuit board may be called a “mother board” and the printed circuitboards connected to it may be called daughterboards. Also, boards of thesame size or similar sizes may sometimes be aligned in parallel.Connectors used in these applications are often called “stackingconnectors” or “mezzanine connectors.”

Regardless of the exact application, electrical connector designs havebeen adapted to mirror trends in the electronics industry. Electronicsystems generally have gotten smaller, faster, and functionally morecomplex. Because of these changes, the number of circuits in a givenarea of an electronic system, along with the frequencies at which thecircuits operate, have increased significantly in recent years. Currentsystems pass more data between printed circuit boards and requireelectrical connectors that are electrically capable of handling moredata at higher speeds than connectors of even a few years ago.

One of the difficulties in making a high density, high speed connectoris that electrical conductors in the connector can be so close thatthere can be electrical interference between adjacent signal conductors.To reduce interference, and to otherwise provide desirable electricalproperties, shield members are often placed between or around adjacentsignal conductors. The shields prevent signals carried on one conductorfrom creating “crosstalk” on another conductor. The shield also impactsthe impedance of each conductor, which can further contribute todesirable electrical properties. Shields can be in the form of groundedmetal structures or may be in the form of electrically lossy material.

Other techniques may be used to control the performance of a connector.Transmitting signals differentially can also reduce crosstalk.Differential signals are carried on a pair of conducting paths, called a“differential pair.” The voltage difference between the conductive pathsrepresents the signal. In general, a differential pair is designed withpreferential coupling between the conducting paths of the pair. Forexample, the two conducting paths of a differential pair may be arrangedto run closer to each other than to adjacent signal paths in theconnector. No shielding is desired between the conducting paths of thepair, but shielding may be used between differential pairs. Electricalconnectors can be designed for differential signals as well as forsingle-ended signals.

Maintaining signal integrity can be a particular challenge in the matinginterface of the connector. At the mating interface, force must begenerated to press conductive elements from the separable connectorstogether so that a reliable electrical connection is made between thetwo conductive elements. Frequently, this force is generated by springcharacteristics of the mating contact portions in one of the connectors.For example, the mating contact portions of one connector may containone or more members shaped as beams. As the connectors are pressedtogether, these beams are deflected by a mating contact portion, shapedas a blade or pin, in the other connector. The spring force generated bythe beam as it is deflected provides a contact force.

For mechanical reliability, many contacts have multiple beams. In someinstances, the beams are opposing, pressing on opposite sides of amating contact portion of a conductive element from another connector.The beams may alternatively be parallel, pressing on the same side of amating contact portion.

Regardless of the specific contact structure, the need to generatemechanical force imposes requirements on the shape of the mating contactportions. For example, the mating contact portions must be large enoughto generate sufficient force to make a reliable electrical connection.

SUMMARY

The inventors have recognized and appreciated that the performance ofinterconnection systems may be significantly improved by providingelectrical connectors that incorporate superelastic materials. The useof superelastic materials may allow for connector designs with contactshapes that provide reliable contact forces in relatively small areas,enabling dense connectors and/or connectors which may improveperformance with high frequency signals.

According to one aspect, an electrical interconnection system includes afirst connector comprising one or more mating contacts and a second,mating connector comprising one or more conductive receptacles. The oneor more mating contacts are misaligned with the one or more conductivereceptacles when the interconnection system is in an unmatedconfiguration. Moving the interconnection to a mated configurationcauses the one or more mating contacts to deform to create one or morecontact points with the conductive receptacles.

According to another aspect, an electrical interconnection systemincludes a first connector comprising one or more superelasticcomponents, and a second, mating connector comprising one or moreconductive receptacles. The one or more superelastic components deformwithout yielding within the one or more conductive receptacles when theinterconnection system is in a mated configuration.

According to a further aspect, an electrical connector comprises areceiving portion including a housing constructed and arranged toreceive a connector blade. At least one superelastic component isdisposed in the housing. The superelastic component deforms within thehousing to create a contact force against the connector blade when theconnector blade is inserted into the receiving portion.

According to yet another aspect, an electrical connector includes one ormore superelastic portions having a wave shape. The superelasticportions are constructed and arranged such that the wave shape isflattened during mating to generate a contact force.

According to still another aspect, an electrical connector includes oneor more shape memory components having a first shape below a transitiontemperature, and a second shape above the transition temperature. Theelectrical connector further comprises one or more receptaclesconstructed and arranged to receive the one or more shape memorycomponents.

According to another aspect, an electrical connector includes aplurality of contact elements disposed in an array. Each of theplurality of contact elements comprises a contact tail and a matingcontact portion. The mating contact portion comprises a superelasticelongated member.

According to yet another aspect, an electrical connector comprises ahousing and a plurality of contact elements disposed in an array. Eachof the contact plurality of contact elements comprises a contract tailand a mating contact portion. The mating contact portion comprisesopposing conductive surfaces fixedly held within the housing. The matingcontact portion further comprises at least one projection extending fromat least one of the opposing conductive surfaces.

It should be appreciated that the foregoing concepts, and additionalconcepts discussed below, may be arranged in any suitable combination,as the present disclosure is not limited in this respect. Further, otheradvantages and novel features of the present disclosure will becomeapparent from the following detailed description of various non-limitingembodiments when considered in conjunction with the accompanyingfigures.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In thedrawings, each identical or nearly identical component that isillustrated in various figures may be represented by a like numeral. Forpurposes of clarity, not every component may be labeled in everydrawing. In the drawings:

FIG. 1 is a plot showing representative stress-strain curves forconventional materials and superelastic materials;

FIG. 2A is a cross-sectional view of one embodiment of a portion of aninterconnection system including two superelastic wires and twoassociated conductive receptacles, in an unmated configuration;

FIG. 2B is a cross-sectional view of the portion of an interconnectionsystem of FIG. 2A, in a mated configuration;

FIG. 3 is a cross-sectional view of another embodiment of a portion ofan interconnection system including two superelastic wires and twoassociated conductive receptacles, in a mated configuration;

FIG. 4A is a cross-sectional view of yet another embodiment of a portionof an interconnection system including a conductive receptacle havingtwo compliant beams on which a plurality of protrusions are formed,configured to receive a superelastic wire;

FIG. 4B is an isometric view of the conductive receptacle of FIG. 4A, asmanufactured from a single sheet and prior to folding;

FIG. 5A is a cross-sectional view of another embodiment of a portion ofan interconnection system including a superelastic wire and a conductivereceptacle including a plurality of angled walls;

FIG. 5B is a schematic representation of the path of the superelasticwire in the mated configuration;

FIG. 5C is an isometric view of an alternative embodiment of aconductive receptacle with protrusions positioned along a helical pathto create a helical path for a wire inserted into the receptacle;

FIG. 5D is an end view of the conductive receptacle of FIG. 5C, takenfrom the perspective of line D-D in FIG. 5C;

FIG. 6 is a cross-sectional view of yet another embodiment of a portionof an interconnection system including two superelastic wires and twoassociated receptacles including a plurality of protrusions formed ascylindrical pegs;

FIGS. 7A and 7B are schematic cross-sectional representations of anembodiment of a portion of an interconnection system including a matingcontact which is coaxially misaligned with a conductive receptacle, inan unmated configuration and a mated configuration, respectively;

FIGS. 8-10 are cross-sectional views of embodiments of portions ofinterconnection systems in which a superelastic wire is included in areceiving portion of the connector;

FIG. 11A is an isometric view of a connector including a plurality ofsuperelastic pins;

FIG. 11B shows the connector of FIG. 11A with a bent pin;

FIG. 11C shows a cross-sectional view of the connector of FIG. 11B;

FIG. 12 is an isometric view of an embodiment of portion of a connectorincluding a superelastic portion attached to a portion made from aconventional material;

FIGS. 13A and 13B are cross-sectional views of one embodiment of aconnector including a superelastic portion formed into the shape of awave, in the unmated and mated configurations, respectively;

FIG. 14A is an isometric view of one embodiment of a mating contactportion of a conductive element in which a superelastic portion iswelded to a backing plate;

FIG. 14B is an isometric view of another embodiment of a mating contactportion of a conductive element in which a superelastic portion isriveted to a backing plate;

FIG. 14C is a cross-sectional view of a portion of an interconnectionsystem including the mating contact portion of FIG. 14B in a matedconfiguration;

FIG. 15 is an isometric view of yet another embodiment of a contactelement of an interconnection system in which a superelastic portion hasan angled wave shape;

FIG. 16A is a cross-sectional view of an embodiment of a portion of aninterconnection system including two shape memory wires below a criticaltransition temperature, in a partially mated configuration;

FIG. 16B is a cross-sectional view of the portion of an interconnectionsystem of FIG. 16A above the critical transition temperature, in a fullymated configuration;

FIG. 17 is a perspective view of an electrical interconnection systemillustrating an environment in which certain embodiments may be applied;

FIG. 18A is a schematic cross-sectional representation of an embodimentof a portion of an interconnection system in an unmated configuration,including two mating contacts which are coaxially misaligned withconductive receptacles;

FIG. 18B is a schematic top-view of the conductive receptacles of FIG.18A, each receptacle having an offset countersink; and

FIG. 18C is a schematic cross-sectional representation of the portion ofthe interconnection system of FIG. 18A in a mated configuration.

DETAILED DESCRIPTION

The inventors have recognized and appreciated that the performance ofinterconnection systems may be significantly improved by providingelectrical connectors that incorporate shape memory materials exhibitingsuperelastic behavior (also known as pseudoelasticity), herein referredto as superelastic materials. Improved performance may be achieved, forexample, by using conductive superelastic members to provide matingcontact structures that reduce or eliminate unterminated “stubs.”Alternatively or additionally, superelastic materials may be formed withcontact shapes that provide reliable contact forces in relatively smallareas, enabling dense connectors. Moreover, in some embodiments, spacingor other characteristics of the mating contact portions may be alteredby deformation of the superelastic material. As a result of suchdeformation, the impedance of the mating contact portions may be variedduring mating, which may provide a uniform impedance or impedancetransition through the mating interface as the connector mates with amating connector.

Superelastic materials may be characterized by the amount of strainrequired for those materials to yield, with superelastic materialstolerating a higher strain before yielding. Additionally, the shape ofthe stress-strain curve for a superelastic material includes a“superelastic” region. Illustrative stress-strain curves for aconventional and superelastic material are shown in FIG. 1.

Superelastic materials may include shape memory materials that undergo areversible martensitic phase transformation when a suitable mechanicaldriving force is applied. The phase transformation may be adiffusionless solid-solid phase transformation which has an associatedshape change; the shape change allows superelastic materials toaccommodate relatively large strains compared to conventional (i.e.non-superelastic) materials, and therefore superelastic materials oftenexhibit a much larger elastic limit than traditional materials. Theelastic limit is herein defined as the maximum strain to which amaterial may be reversibly deformed without yielding.

Superelastic behavior is exhibited by many shape memory materials whichexhibit the shape memory effect. Similar to superelasticity, the shapememory effect involves a reversible transformation between the austeniteand martensite phases with a corresponding shape change. However, thetransformation in the shape memory effect is driven by a temperaturechange, rather than mechanical deformation as in superelasticity. Inparticular, a material which exhibits the shape memory effect mayreversibly transition between two predetermined shapes upon atemperature change which crosses a transition temperature. For example,a shape memory material may be “trained” to have a first shape at lowtemperatures (below the transition temperature), and a second, differentshape above the transition temperature. Training a particular shape fora shape memory material may be accomplished by constraining the shape ofthe material and performing a suitable heat treatment.

FIG. 1 depicts representative stress-strain curves for conventionalmaterials and for superelastic materials, which in this example arematerials that undergo a reversible martensitic phase change from anaustenite phase to a martensite phase. The stress-strain curve 10 for aconventional material exhibits elastic behavior up to a yield point 12corresponding to an elastic limit 14. The stress strain curve for asuperelastic material is depicted as curve 20; the arrows on the curveindicate the stress-strain response for loading and unloading. Duringloading, superelastic materials exhibit elastic behavior up to a firsttransition point 26 a, after which the transformation from austenite tomartensite begins and the stress-strain curve exhibits a characteristicplateau 28 a, herein referred to as the superelastic regime. In thesuperelastic regime, the shape change associated with the martensitetransformation allows the material to accommodate additional strainwithout a significant corresponding increase in stress. When all of thesuperelastic material has been converted to martensite, the superelasticmaterial may reach a yield point 22 corresponding to an elastic limit24. During unloading, the martensite phase transforms back to theaustenite phase; the transformation begins at a second transition point26 b and may occur at a lower stress than the transformation duringloading, as indicated by the second plateau 28 b.

As described above, the elastic limit of superelastic materials may besubstantially larger than those of conventional materials. For example,some superelastic materials may be deformed to about 7% to 8% strain ormore without yielding; in contrast, many conventional materials, such asmetal alloys commonly used in electrical connectors, yield at 0.5%strain or less. Therefore, superelastic materials may enable designs forseparable electrical connectors which utilize relatively large localdeformations that are not possible with conventional materials withoutresulting in yielding and associated permanent damage to the connector.In particular, the inventors have recognized and appreciated that thelarge elastic limit of superelastic materials may be beneficial forproviding reliable connections in the mating interface of an electricalconnector. For example, the substantially flat stress-strain response ofsuperelastic materials in the superelastic regime may allow forcomponents made from superelastic materials to provide the same contactforce over a large range of deformations. Therefore, superelasticcomponents may allow for design tolerances that are larger compared towhat is possible with conventional materials.

In some embodiments, the plateau 28 a in the stress-strain response of asuperelastic material may enable connector designs which feature asubstantially constant mating force over an extended range ofdeformations. Specifically, as described above, when a superelasticmaterial is deformed in the superelastic regime, additional appliedstrain may be accommodated via a phase transition from an austenitephase to a martensite phase without a substantial increase in theapplied stress. Such a response may allow for more facile and/orreliable connections between components of an interconnection system.For example, in some embodiments, an initial deformation applied to aconnector element made from superelastic material during an initialstage of the mating process may be sufficient to deform the connectorelement into the superelastic regime. Therefore, the remainder of themating process, including subsequent deformation of the superelasticconnector element, may be carried out with little, if any, additionalrequired force. In contrast, connector elements made from conventionalmaterials may require an increasing force to achieve additionaldeformation.

Accordingly, in some embodiments, a connector may be designed with anominal mating state in which beams or other members made ofsuperelastic materials are deflected near the middle of the superelasticregion. Because of manufacturing tolerances in the connector and thesystem in which the connector might be installed, members in a connectormay be deflected more or less than designed for a nominal mating state.In a connector made with superelastic members, over a relatively wideworking range, more or less deflection will still result in the membersoperating in their superelastic region. As a result, the contact forceprovided by those members will be approximately the same over the entireworking range. Such a uniform force, despite variations attributable tomanufacturing tolerances, may provide more reliable electricalconnectors and electronic systems using those connectors.

Furthermore, the inventors have appreciated that superelastic materialsmay enable connector designs which may provide improved signal integrityfor very high frequency signals, allow for a higher density ofconnectors, and/or provide improved reliability over time compared toexisting connector designs which are limited by the mechanicalproperties of conventional connector materials.

Accordingly, in some embodiments, an electrical connector may includeone or more components made from superelastic materials which areconstructed and arranged to substantially deform during mating to createthe contact force required for a reliable electrical connection. Suchembodiments may also include a portion of a connector which is shapedand/or configured to cause such deformation. For example, in someembodiments, a male portion of a connector may comprise one or morewires made from a superelastic material, herein referred to assuperelastic wires, which are substantially undeformed when theconnector is in an unmated configuration. A female portion of theconnector may comprise one or more conducting receptacles which define apassage or channel sized and shaped to receive the wires, and thereceptacles may further include one or more protrusions transverse tothe axis of the channel. During mating, the wires are inserted into thepassages in a direction aligned with the axis of the channel, and theprotrusions cause the wires to deform such that the wires contact theprotrusions and/or the sidewalls of the passages. The deformed shape ofthe superelastic wires provides a restoring force which creates thecontact force necessary to form a reliable electrical connection.Furthermore, the force may be sufficient to break through any oxide onthe surfaces of the portions of the connectors which come into contact.When unmated, the superelastic wires may return to their original,undeformed geometry. It should be understood that in such embodiments,the use of superelastic components may enable designs in which localstrains in the superelastic components would exceed the elastic limit ofconventional materials, and therefore such embodiments would not bepossible using conventional materials without causing permanentdeformation and associated damage to the connector.

FIGS. 2A and 2B depict an illustrative embodiment of a portion of aninterconnection system 200 according to the present disclosure. Theinterconnection system comprises a male portion 202 and a female portion206. These portions may represent the mating interface portions ofmating connectors. For example, male portion 202 may be a portion of abackplane connector and female portion 206 may be a portion of adaughtercard connector configured for mating to the backplane connector.However, it should be appreciated that the mating contact portionsillustrated in FIGS. 2A and 2B, and throughout this disclosure, may beused in any suitable mating configuration. For example, one or more ofthe mating interface portions may be a portion of a cable connector or astacking connector.

Moreover, it should be appreciated that FIGS. 2A and 2B show only aportion of the mating interface of a connector. For simplicity, in someinstances, only a single conductive element or a single pair ofconductive elements is illustrated. However, the illustrated portionsmay be repeated multiple times in a connector to provide an array, whichmay be a two dimensional array, of conductive elements. The spacing ofthe array may provide a spacing between conductive elements on the orderof 2.5 mm or less, with some embodiments having spacing between 0.25 and2.5 mm.

In the embodiment illustrated, the illustrated portion is a portion of amodule for an electrical connector, including a signal pair andsurrounding shielding acting as a ground conductor. Such modules, andconnectors made from such modules, are described in co-pending U.S.application Ser. Nos. 14/603,300 and 14/603,294, which are herebyincorporated by reference in their entireties. As described in thoseapplications, the mating contact portions may be formed at one end of aconductive element passing through a connector. An opposite end of theconductive elements may include a contact tail, adapted for attaching toa printed circuit board or other substrate to which the connector isattached. The contact tail and the mating contact portion may be joinedby an intermediate portion passing through the connector. In someembodiments, some or all of these portions of the conductive elementsmay be made of superelastic material. For example, the mating contactportions and the contact tails may be superelastic. Those portions maybe joined by an intermediate portion that is more conductive. In otherembodiments, only the mating contact portion in one module may be formedof a superelastic material, and all other portions of the conductiveelements may be formed of a metal conventionally used in an electricalconnector.

Depending on the particular embodiment, the superelastic material mayhave a suitable intrinsic conductivity or may be made suitablyconductive by coating or attachment to a conductive material. Forexample, a suitable conductivity may be in the range of about 1.5 μΩcmto about 200 μΩcm. Examples of superelastic materials which may have asuitable intrinsic conductivity include, but are not limited to, metalalloys such as copper-aluminum-nickel, copper-aluminum-zinc,copper-aluminum-manganese-nickel, nickel-titanium (e.g. Nitinol), andnickel-titanium-copper. Additional examples of metal alloys which may besuitable include Ag—Cd (approximately 44-49 at % Cd), Au—Cd(approximately 46.5-50 at % Cd), Cu—Al—Ni (approximately 14-14.5 wt %,approximately 3-4.5 wt % Ni), Cu—Au—Zn (approximately 23-28 at % Au,approximately 45-47 at % Zn), Cu—Sn (approximately 15 at % Sn), Cu—Zn(approximately 38.5-41.5 wt % Zn), Cu—Zn—X (X═Si, Sn, Al, Ga,approximately 1-5 at % X), Ni—Al (approximately 36-38 at % Al), Ti—Ni(approximately 49-51 at % Ni), Fe—Pt (approximately 25 at % Pt), andFe—Pd (approximately 30 at % Pd).

In some embodiments, a particular superelastic material may be chosenfor its mechanical response, rather than its electronic properties, andmay not have a suitable intrinsic conductivity. In such embodiments, thesuperelastic material may be coated with a more conductive metal, suchas silver, to improve the conductivity. For example, a coating may beapplied with a chemical vapor deposition (CVD) process, or any othersuitable coating process, as the disclosure is not so limited. Coatedsuperelastic materials also may be particularly beneficial in highfrequency applications in which most of the electrical conduction occursnear the surface of conductors. As described in more detail below, insome embodiments, the conductivity of a connector element including asuperelastic material may be improved by attaching a superelasticmaterial to a conventional material which may have a higher conductivitythan the superelastic material. For example, a superelastic material maybe employed only in a portion of the connector element which may besubjected to large deformations, and other portions of the connectorwhich do not deform significantly may be made from a conventional (highconductivity) material.

An electrical connector of the type that might be improved through theuse of superelastic materials is illustrated below in FIG. 17. Thatconnector is configured as a right angle, backplane connector. However,it should be appreciated that the specific form of connector is not alimitation on the invention. Mating interfaces as described herein maybe applied, for example, in stacking connectors, mezzanine connectors,or cable connectors, for example. Alternatively or additionally,disclosed techniques may also be applied in other separable interfacesin electronic systems, such as between components and printed circuitboards or between sockets and electronic devices inserted into thesockets.

In some embodiments, the connectors, or other components of anelectrical interconnection system, incorporating superelastic materialsmay be designed to propagate signals as a differential pair.Accordingly, some embodiments may be described in connection with themating portions of a differential pair of conductive elements, such asmay exist at the mating interface of connectors as shown in FIG. 17.However, it should be appreciated that techniques as described hereinare not limited to use in differential signal conductors. In someembodiments, superelastic materials may be used to form conductiveelements shaped to carry single-ended signals. Moreover, it should berecognized that techniques as described herein are not limited for useon signal conductors. In some embodiments, superelastic materials may beused to form conductive elements shaped to carry return currents, serveas reference conductors and/or act as shields. Conductive elements usedin these ways may be combined to form coax, twinax, triax or otherconductive structures. Such conductive elements may form portions ofcables or cable assemblies, electrical connectors, and/or othercomponents in an interconnection system.

In the embodiment illustrated in FIGS. 2A and 2B, male portion 202includes two superelastic wires 204 supported by a housing 216. Femaleportion 206 includes a housing 218 holding two substantially rigid,conductive receptacles 208. In some embodiments, the housing may be madeof any suitable material, and may be insulative. An insulative housingmay be formed, for example, by molding a thermoplastic material filledwith glass fibers or other suitable material using techniques as areknown in the art. However, in some embodiments, portions of the housingmay be formed of a lossy material, as described in the co-pending U.S.application Ser. Nos. 14/603,300 and 14/603,294, which are herebyincorporated by reference. The housing also may have any suitable sizeand may be configured to provide a connector with a desired spacingbetween conductors. For example, as described above, in someembodiments, the spacing of conductors in a connector array may bebetween 0.25 mm and 2.5 mm.

The female portion 206 also includes shielding 220 around the housing218 which may act as a ground conductor. The shielding may be made ofany suitable conductive material and may be arranged around any suitableportion of the housing.

Conductive receptacles 208 may be formed of any suitable material,including materials used to form mating contact portions of connectorsas is known in the art. Such materials may include copper alloys, suchas phosphor bronze. However, in the embodiment illustrated, receptacles208 are held within housing 218 and do not need to deflect during matingto ensure proper operation. Accordingly, receptacles 208 may be made ofmaterials that are less springy than materials conventionally used tomake mating contact portions of an electrical connector. The matingcontact portions may be coated with gold or other materials to resistoxidation or otherwise promote good electrical contact betweenreceptacles 208 and superelastic wires 204.

As depicted in FIG. 2A, in the unmated configuration, the wires aresubstantially straight and undeformed. The receptacles 208 definechannels which are bounded by conductive surfaces. The channels have anaxis that is parallel with the mating direction of the connectors suchthat, as the connectors are brought together, superelastic wires 204will each enter a channel of a receptacle. In the embodimentillustrated, the receptacles 208 are nominally cylindrical and include aplurality of protrusions 210 extending perpendicular to the axis of thechannels; in the depicted embodiment the protrusions are arranged onopposing sides of the receptacles and are configured as angled portions.

The receptacles 208 and protrusions 210 together define two tortuouspathways 212 to receive the wires 204. As depicted in FIG. 2B, whenmated, the wires 204 contact the protrusions 210 and deform to followthe pathways 212, and therefore make contact with the receptacles 208 atmultiple locations, including along the protrusions as well as along thesidewalls of the receptacles. As can be seen, the wires 204 pressagainst the protrusions and are deflected.

Although certain aspects of an interconnection system, have beendescribed above with reference to the embodiment illustrated in FIGS. 2Aand 2B, it should be understood that those aspects and other aspectsdisclosed herein may be applicable to all embodiments described in thepresent disclosure. Furthermore, different embodiments described hereinmay be used separately, or may be used in any suitable combination, asthe disclosure is not so limited.

FIG. 3 depicts another embodiment of mated connector modules in aninterconnection system 300. Similar to the above described embodiment,one of the modules comprises two superelastic wires 304 received in twosubstantially rigid, conductive receptacles 308 of a mating module.Protrusions 310 are arranged in the passages on a single side, andincrease in size along a longitudinal direction of the receptacles. Asdepicted in FIG. 3, the protrusions are configured to deform thesuperelastic wires 304 toward the sidewalls of the receptacles 308, suchthat in the mated configuration, the superelastic wires contact thereceptacles at multiple points including at the protrusions 310 andalong the sidewalls of the receptacles.

In the above described embodiments, the receptacles are depicted assubstantially rigid, and only the component made from the superelasticmaterial (e.g. superelastic wire) may move and/or deform during mating.Alternatively, in some embodiments, a receptacle may include one or morecompliant members, such as beams formed from conventional materialswhich may, or may not, include one or more protrusions. Such compliantmembers may also deform, but to a smaller extent than the superelasticcomponents such that the deformation of the compliant members does notexceed the elastic limit and therefore the receptacle does not becomepermanently deformed during mating.

FIGS. 4A and 4B depict an illustrative embodiment of a portion of aninterconnection system 400 including a housing 418 which holds aconductive receptacle 408. As with the other embodiments illustratedherein, the receptacle may form a portion of a first connector. Multiplelike receptacles may be included in the connector. Likewise, the portionof the conductive element illustrated may be a portion of the conductiveelement. For example, an intermediate portion and a contact tail may bepresent, though not illustrated. In this example, the receptacleincludes two compliant beams 414 and 416 on which a plurality ofprotrusions 410 is formed. In the depicted embodiment, the receptacle408 is formed from a single piece which includes a fold 420 such thatthe compliant beams 414 and 416 form opposing surfaces. Such a form maybe formed using known forming processes or in any other suitable way.

During mating, a superelastic wire 404 from a mating connector may beinserted into the receptacle 408. In the embodiment shown, superelasticwire 404 is inserted between the compliant beams 414 and 416 causing thebeams to deflect, and therefore generating a contact force between theprotrusions 410 and the superelastic wire. As depicted in FIG. 4A, thehousing 418 may limit the deformation of the compliant beams duringmating to further urge deformation of the superelastic wire 404 andtherefore increase the contact force, and also to reduce the possibilityof deforming the compliant beams 414 and 416 past their elastic limit.As depicted in FIG. 4B, the receptacle 408 may be manufactured as asingle flat sheet, and subsequently folded to form the desired connectorgeometry. The beams may be formed at an end of an elongated conductiveelement, with the rest of the conductive element forming an intermediateportion and a contact tail.

Depending on the particular embodiment, protrusions may be arranged inany suitable pattern. In the embodiment illustrated, protrusions havehemispherical upper surfaces and are positioned in pairs. The spacebetween the hemispherical portions may serve as a guide for the wire asit is being inserted. Moreover, it should be appreciated that FIGS. 4Aand 4B illustrate a single conductive element. Such a design may beappropriate for a single-ended signal. Alternatively, a mating contactstructure as illustrated may be duplicated to provide a pair forcarrying a differential signal. In either case, shielding may bepositioned around or adjacent to the structure shown.

FIGS. 5A and 5B depict another embodiment of a portion of aninterconnection system 500 according to the present disclosure. Theportion includes a housing 518 which holds a receptacle 508. As in otherembodiments, the housing may be insulative and may include lossyportions. As in the embodiments of FIGS. 2A . . . 4B, the receptacle mayinclude protrusions that deflect an elongated superelastic memberinserted into the receptacle. In this example, the receptacle includes aplurality of angled walls 510 extending outward from a back wall 512 ofthe receptacle, which are constructed and arranged to deflect asuperelastic wire 504 during mating.

In the embodiment illustrated, the housing 518 includes projections 530a and 530 b arranged in a region 532. The projections may be made fromthe same insulative and/or lossy materials as the housing 518. Such aconfiguration may reduce abrupt impedance discontinuities or variationsif the connector pieces are not pressed fully together. Specifically,when the wire 504 is inserted into the region 532, it is surrounded atleast on one side by an insulator, and therefore the impedance in region532 may be closer to the nominal impedance of the fully mated connectorcompared to a configuration in which a segment of the wire 504 wassurrounded entirely by air.

The arrows in FIG. 5B are a schematic representation of the tortuouspath 514 of the superelastic wire 504 in the mated configuration. Eachbend in that tortuous path comprises a deflection point for thesuperelastic wire. The deflection provides an appropriate contact forceto ensure reliable electrical connection. However, those bends have aradius large enough that they do not generate a stress that would exceedthe yield stress and cause plastic deformation of the wire. In this way,relatively high forces can be generated while allowing the connectors tomate and unmate reliably over many cycles, because the superelastic wirewill return to its original shape when the connectors are unmated.

FIGS. 5C and 5D depict a further embodiment of a portion of aninterconnection system 550 including a conductive receptacle 552; FIG.5D depicts an end view of the receptacle taken from the perspective ofline D-D. As with the other embodiments illustrated herein, thereceptacle may form a portion of a first connector. Multiple likereceptacles may be included in the connector. Likewise, the portion ofthe conductive element illustrated may be a portion of the conductiveelement. For example, an intermediate portion and a contact tail may bepresent, though not illustrated. In this example, the receptacleincludes a plurality of protrusions 554 are distributed along a helicalpath on the circumference of the receptacle 552 so as to define ahelical path for a wire inserted into the receptacle. The protrusions554 may be distributed along any suitable helical path, including auniform and/or non-uniform helical path, and may be spaced evenly alongthe helical path, or alternatively at irregular, as the disclosure isnot so limited. Such a configuration may cause a wire, such as asuperelastic wire, to twist and/or deform along the helical path as itis inserted into the receptacle, thereby urging the tip of the wire tomaintain contact with a side wall of the receptacle over a large rangeof insertion distances. Such contact with the sidewall of the receptaclemay substantially reduce or prevent the formation of stubs, as describedin more detail below. FIG. 6 depicts yet another embodiment of a portionof an interconnection system 600. As with other embodiments, theillustrated portion may be just a portion of a module forming aconnector. Multiple such modules may be held in a housing or othersupport structure to form full connectors.

In the depicted embodiment, the receptacles 608 are supported by ahousing 618 and include a plurality of protrusions 610 are formed ascylindrical pegs extending from a back wall 612 of the receptacles 608.The space between the pegs may define channels into which a superelasticalloy from a mating connector may be inserted. Similar to the abovedescribed embodiments, the protrusions 610 deflect superelastic wires604 in the mated configuration to generate an appropriate contact force.In this embodiment, intermediate portions 620 of the superelastic wires604 are attached to contact tails 622. The contact tails also may bemade from a superelastic material, or alternatively they be made from aconventional material. The contact tails 622 may enable attachment of aportion of the interconnection system to a printed circuit board orother substrate.

The embodiment depicted in FIG. 6 further includes additional contactelements 624 which may act as ground conductors. The additional contactelements 624 may, or may not, be made from a superelastic material. Whenmated, contact elements 624 are received by passages 626. Depending onthe particular embodiment, contact elements 624 may make contact withpassages 626 along sidewalls of the passages; in some instances, thepassages 626 may include one or more protrusions or projections arrangedto create contact points with the contact elements 624. In the depictedembodiment, contact elements 624 are attached to separate contact tails628. However, it should be understood that the contact elements 624 andcontact tails 628 may alternatively be formed as a single piece in someembodiments, as the disclosure is not so limited. Furthermore, contactelements 624 may be formed as cylindrical wires, flat blades, or anyother suitable shape.

In this embodiment, the tip of the superelastic wire is shown to beslightly rounded. In some embodiments, the wire may have a rounded tipor tip of any other suitable shape to provide a tapered surface that mayreduce the end of the wire catching on a projection or other structure.The tip, for example, may be angled.

In view of the above described embodiments, it should be understood thata connector which includes one or more protrusions formed in and/or onan associated receptacle and configured to deflect and/or deform asuperelastic member, such as a wire, during mating may be constructedand arranged in any suitable manner. For example, the protrusions mayhave any suitable shape, and may be arranged on opposing sides of areceptacle, on a single side of a receptacle, or in any other suitablearrangement, as the disclosure is not so limited. Accordingly, asuperelastic wire may deflect within a receptacle in a single direction,in multiple directions, or in any combination of directions such as in atortuous path. Furthermore, although superelastic wires are describedabove, a component made from a superelastic material which deforms in anassociated receptacle may have any suitable geometry including, but notlimited to, a cylindrical or wire-like geometry, a flat beam orblade-like geometry, or an elongated prism geometry with any suitablecross-sectional shape.

It should also be understood that a connector may include any suitablenumber of conductive paths comprising superelastic components, such aswires. For example, the embodiments depicted in FIGS. 2, 3 and 6 includetwo superelastic wires which may be arranged to carry signals as adifferential pair. FIGS. 4 and 5 depict connectors which include onlyone superelastic wire to carry a signal. Additionally, in someembodiments, a connector also may include any suitable number ofcomponents made from conventional materials, as the disclosure is not solimited.

In some embodiments, a mating contact, such as a superelastic wire, maybe deformed without any protrusions in a conducting passage. Forexample, in some embodiments, a mating contact and a conductivereceptacle may be arranged in a coaxially misaligned configuration suchthat the mating contact is deflected by the sidewalls of the receptacleduring mating. FIGS. 7A-7B schematically depict an illustrative exampleof one such embodiment. FIG. 7A shows two connectors in an unmatedconfiguration; as shown in the figure, a wire 704 of a first connectoris misaligned with a receptacle 708 of a second connector. Thereceptacle may be shaped with an opening 710 that is tapered from alarger diameter at the surface of the receptacle to a smaller diameter,which may facilitate insertion of the wire into the receptacle. In someinstances, the tapered opening may be formed by countersinking theopening of the receptacle to form a generally conical enlargement of theopening of the receptacle. As discussed in more detail below, thecountersink may be coaxially aligned with the opening, or alternatively,the countersink may be coaxially offset relative to the opening.

In some embodiments, the illustrated receptacle 708 may be a matingcontact portion of a conductive element in a connector. The wire 704 maybe a mating contact portion of a mating connector. However, in otherembodiments, the receptacle may be a via 708 formed in a printed circuitboard or other substrate. In this embodiment, the wire, rather thanforming a mating contact portion of a conductive element in connector,may be a contact tail. Such a structure may likewise be repeated in anarray to attach multiple conductive elements within the connector. Asdepicted in FIG. 7B, when mated, the wire is deflected by the sidewallsof the via such that one or more contact points 705 are formed betweenthe wire and the sidewalls of the via. In particular, the misalignmentof the wire relative to the receptacle causes the wire to deform (i.e.,elastically and/or plastically) as the connectors are moved towards themated configuration. In some instances, the connectors may include oneor more alignment features (not depicted) arranged to establish andmaintain the misalignment between the wire and the receptacle duringmating. For example, the alignment features may interact prior to thewire and receptacle moving to the mated configuration, and thepositioning of the guides relative to the wire and receptacle may definethe misalignment.

FIGS. 18A-18C schematically depict another illustrative embodiment of aportion of an electrical interconnection system in which one or moremating contacts are deformed without any protrusions in correspondingconducting passages. In particular, FIG. 18A shows the connectors of theinterconnection system in an unmated configuration, and FIG. 18C showsthe connectors in a mated configuration. In this embodiment, a firstconnector of the interconnection system includes two mating contacts1804 that are misaligned with corresponding conducting receptacles 1808in a second connector. Similar to the embodiment described above withregard to FIGS. 7A-7B, the conducting receptacles may be mating contactportions of a conductive element in a connector, or they may be viasformed in a printed circuit board or other substrate.

In this embodiment, the misalignment is the result of the pair of matingcontacts 1804 being more closely spaced than the pair of receptacles1808. However, misalignment may result from the mating contacts 1804being more widely spaced than the pair of receptacles 1808. In thisexample, misalignment is achieved by positioning a plurality of contactswith different spacing than the receptacles into which those contactsare inserted. With this geometry, the set of contacts cannot bepositioned so that all contacts of the set align with the receptacles inwhich they are to be inserted. Alternatively or additionally,misalignment may be achieved in an interconnection system that hasalignment features (not shown). As is known in the art, components of aninterconnection system may have components for guiding one member of aninterconnection system into contact with a mating component of theinterconnection system, for example guide pins or chamfered walls of ashell may guide two connectors into a desired relative position. Thedesired relative position may result in the contacts of one componenthaving their elongated axes being parallel to, but offset from, the axesof the receptacles into which those contacts are to be inserted.

As best illustrated in FIG. 18B, the receptacles 1808 may includecountersinks 1810 to provide tapered openings to the receptacles. Inthis manner, the countersinks may aid in guiding the mating contacts1804 into the receptacles 1808 when the interconnection system is movedfrom the unmated configuration to the mated configuration. Further, asillustrated in FIG. 18B, in some instances the countersinks 1810 may beoffset relative to the receptacles 1808. In particular, in the depictedembodiment, the receptacles are generally cylindrical, and thecountersinks are formed as conical openings in the receptacles with thecenter of the conical openings offset relative to the centers of thereceptacles. Further, the countersinks are offset relative to thereceptacles in a direction corresponding to the misalignment of themating contacts relative to the receptacles. In this manner, relative toa configuration in which the countersinks are aligned with thereceptacles, the offset configuration may position more of a taperedsurface area where the tapered surface can interact with the matingcontacts to aid in guiding the mating contacts into the receptacles.However, it should be understood that the current disclosure is notlimited to configurations in which the openings of the conductivereceptacles have countersinks that are offset relative to thereceptacles.

FIG. 18C shows the interconnection system in a mated configuration.Similar to FIGS. 7A-7B, the coaxially offset configuration of the matingcontacts 1804 relative to the receptacles 1808 causes the matingcontacts to deform against the sidewalls of the receptacles duringmating. In particular, the spacing between the mating contacts isdifferent than the spacing between the receptacles such that the matingcontacts undergo deformation as they are received in the receptacleswhen moving the connectors towards a mated configuration. In thismanner, one or more contact points 1805 are formed between the matingcontacts and the receptacles to complete the electrical connection.Although the mating contacts 1804 are depicted as having a smallerspacing than the receptacles 1808 in the unmated configuration, thusresulting in the mating contacts deforming outwardly (i.e., away fromone another), it should be understood that the disclosure is not limitedin this regard. For example, in other embodiments, the receptacles maybe misaligned relative to the mating contacts so as to cause the matingcontacts to deflect inwardly towards one another (i.e., the matingcontacts may have a larger spacing than the receptacles in the unmatedconfiguration).

In some instances, a wire, such as wire 704 in FIGS. 7A-7B or matingcontacts 1804 in FIGS. 18A and 18C, may be made from a superelasticmaterial, and therefore the wire may be able to undergo largedeformations upon mating, and subsequently recover its original shapeupon removing the wire from the receptacle or via 708. However, itshould be understood that the current disclosure is not limited tosuperelastic wires or mating contacts. For example, in some embodiments,the wire 704 or mating contacts 1804 may be made from a compliantmaterial that is operated at stresses that do not exceed the yieldstress. In further embodiments, the wire 704 or mating contacts 1804 mayundergo at least some permanent deformation (i.e., plastic deformation)upon mating.

The designed misalignment between contacts and receptacles as shown inFIGS. 18A-18C may be employed with other interconnection configurations,including other configurations described herein. Although thereceptacles 708 and 1808 in FIGS. 7A-7B and 18A-18C, respectively, aredepicted as having generally smooth sidewalls, it should be understoodthat other configurations also may be suitable, as the currentdisclosure is not limited in this regard. For example, in someembodiments, the receptacles may include one or more projectionsextending from the sidewalls and arranged to further deform the matingcontacts as the mating contacts are received in the receptacles. In thismanner, the projections may aid in forming contact points between themating contacts and receptacles when the connectors are mated. As aspecific example, superelastic wire 504 and receptacle 508 (FIGS. 5A-5D)may be misaligned.

In some embodiments, multiple mating contacts and receptacles may bearranged in an array with each mating contact misaligned with acorresponding receptacle. In some instances, each mating contact ismisaligned in the same manner (e.g., along the same direction and/or bythe same distance) relative to the corresponding receptacles.Alternatively, multiple pairs of mating contacts and receptacles, suchas those depicted in FIGS. 18A-18C, may be arranged to form an array.Accordingly, it should be understood that connectors includingmisaligned mating contacts and receptacles may be arranged in anysuitable configuration.

As a specific example, the misalignment may be applied to all of thesignal conductors in an interconnection system. Ground contacts may bemade of conventional materials with conventional alignment. Also, itshould be appreciated that the misalignment and offset countersinktechniques described herein may be used separately or together.Moreover, these techniques may be used with any suitable spacing.However, these techniques may enable small diameter vias in a printedcircuit board (forming the receptacles for mounting a connector). As aspecific example, the contact may be formed of a wire with a diameter inthe range of 0.005-0.010″ in some embodiments. In other embodiments, thediameter of the wire may be 0.006-0.008.″ The drilled diameter of thevias may be less than 0.0157,″ a diameter conventionally consideredsmall. In some embodiments, the drilled diameter may be in the range of0.0100-0.0150″. In other embodiments, the drilled diameter may be in therange of 0.0120-0.0140″ or 0.0110-0.0120″ or 0.0100-0.0120″. A specificexample may be 0.0130″.

In some embodiments, the interconnection system may include alignmentfeatures that, rather than position the wire off center relative to thereceptacle, align the wire with the receptacle. After the wire isinserted into the receptacle, the connector with the wire may bedisplaced to create a lateral force.

As described above, incorporating superelastic components intoelectrical connectors may enable designs with improved electricalproperties. More specifically, such designs may provide improved signalintegrity for high frequency signals, such as frequencies in the GHzrange, including up to about 45-50 GHz or higher. One importantcharacteristic of connectors incorporating superelastic components whichmay enable such designs is the ability to reduce or eliminate stubs in aconnector. A stub may be formed if there is an unterminated portion of amating contact of a connector that extends beyond a contact point.Reflections of signals in stubs can result in interference, leading tosignificant signal degradation. As shown in FIGS. 2-7, the ability ofsuperelastic components to deform significantly over small distances,i.e. their ability to undergo small radius of curvature deformationwithout yielding, allows for designs which may shorten or eliminatestubs. For example, as depicted in FIG. 2B, the end 205 of thesuperelastic wire 204 contacts the conducting sidewall of the receptacle208 such that no stub results in the mated connection.

Although in the above described embodiments, a superelastic componentmay be a wire in a male portion of a connector, the inventors have alsorecognized and appreciated that in some embodiments it also may bebeneficial to alternatively or additionally include a component madefrom a superelastic material in a female, or receiving portion of aconnector. For example in some embodiments, a superelastic wire ormember of other shape may be included in a receiving portion of aconnector constructed and arranged to receive a conventional connectorblade. Such embodiments may enable connector designs which providereliable connections over a range of insertion distances of theconnector blade, and may also allow for improved electronic performanceby reducing stubs. Furthermore, in some instances, such embodiments maybeneficially provide backward compatibility with existing connectorcomponents.

FIG. 8 depicts one illustrative embodiments of a portion of aninterconnection system 800 which includes a housing 802 and asuperelastic wire 806 in a receiving portion of the connector. As in theabove described embodiments, the portion illustrated may represent themating contact portion of a module. Multiple such modules may be heldtogether in an array to form the mating interface of a connector.Moreover, though not illustrated, the modules may include intermediateportions and contact tails, to enable the connector to be attached to aprinted circuit board or other substrate. A member inserted into themodule for mating may be a mating contact portion of conductive elementin a mating connector. Multiple such conductive elements may be arrangedin an array so that the mating contact portions of the two connectorsare aligned for mating. The conductive elements of the mating connectormay similarly include intermediate portions, which may be held in ahousing, and contact tails that extend from the housing for attachmentto another component, such as a printed circuit board or cable.

In the embodiment illustrated, some of the conductive elements in themating connectors may be formed as composites, including portions thatare made of a superelastic material and other portions that are made ofmetal as conventionally used in an interconnection system. Compositeelements may provide a desirable combination of mechanical andelectrical properties. In the embodiment illustrated the compositeconductive element is in the receptacle portion of the connector.

As illustrated, a first end of the superelastic wire is attached to abeam 808 at a first attachment point 810. Here attachment point 810 isimplemented with a plurality of bands, integrally formed with beam 808.The bands are bent around superelastic wire 808 and deformed to hold thewire in place. However, it should be appreciated that attachment 810 maybe implemented in any suitable way, including soldering, welding orbrazing, and may be implemented with straps, rivets or other elementsthat need not be integral with beam 808.

Beam 808 may be formed of phosphor bronze or other suitable conductivemetal and need not be superelastic. The beam 808 features a cutout 812in a portion of the beam 808 sized to allow a portion of thesuperelastic wire 806 to pass through the cutout, such that a second endof the wire may attach to the beam at a second attachment point 814.Second attachment point 814 may be formed by inserting wire 806 intoholes in beam 808. Here, beam 808 is bent such that there are two holes.The holes may be positioned to be off an axis of wire 806 in itsdesigned shape to provide frictional attachment of wire 806 to beam 808.Soldering, welding, brazing or other suitable attachment techniques maybe used instead of or in addition to frictional engagement.

A conventional connector blade 804 may be inserted into an opening ofthe housing 802 during mating, and the superelastic wire 806 may deformas the blade 804 is moved towards a mated position such that a restoringforce in the superelastic wire 806 creates the desired mating force.Here, wire 806 has a length that exceeds the working distance or workingrange of the interconnection system. The working range, sometimes called“wipe,” indicates the range of distances separating two connectors overwhich electrical connection will still occur, for connectors having thedesigned nominal dimensions. Having a working range means that matingcontact portions of the connectors will be in contact before theconnectors are fully pressed together such that the mating contactportions will slide against each other as the connectors are pressedtogether. Sliding may remove oxides and other contaminants on matingsurfaces and promote reliable electrical connection. In addition, aworking range allows electrical connection even if one or both to theconnectors deviates from the nominal dimensions by less than the workingrange. For both of these reasons, an interconnection system may bedesigned with a working range of 2-4 mm. Accordingly, in someembodiments, wire 806 may have a length in this range.

In some embodiments, beam 808 may be separated from housing 802 suchthat the beam deflects towards the housing when blade 804 is inserted.Such deflection may ensure that superelastic wire 806, which is attachedto beam 808, is forced towards blade 804 to ensure sufficient contactforce for reliable mating. However, in the embodiment illustrated, beam808 has a portion contacting a first wall 820 of housing 802 withoutdeflection. Accordingly, beam 808 may not deflect upon mating. Beam 808may, however, be shaped to deform upon mating such that, as blade 804 isinserted the width of beam 808 may decrease to accommodate for spaceoccupied by blade 804. Such a configuration may accommodate formanufacturing tolerances, while ensure that superelastic wire 806 isforced towards blade 804 to ensure sufficient contact force for reliablemating. In the embodiment illustrated, beam 808 has curves and bendsthat enable the beam to be compressed.

In the embodiment illustrated, beam 808 has a distal end that is shapedto guide blade 804 into the receptacle without mechanical stubbing. Ascan be seen in the example of FIG. 8, the portion of beam 808 with whichblade 804 first makes contact is curved, with a convexity that guidesblades 804 towards a second wall 822 of housing 802 surrounding thereceptacle. As can also be seen, the distal end of blade 804 issimilarly shaped for this guiding function. In the illustratedembodiment, blade 804 has a tapered tip. Accordingly, blade 804, as itis inserted, will be urged against the second wall 822 of housing 802.In this way, blade 804 will slide between superelastic wire 806 and thesecond wall, enabling mating force to be generated by deformation ofwire 806. Moreover, the distal end of beam 808 may be configured toprovide a contact point 824 on beam 808. That configuration providesonly a very small stub on blade 804, improving electrical performance ofthe interconnection system, particularly at high frequencies.

As depicted in FIG. 8, the connector is configured such that thesuperelastic wire 806 includes a bend when the connector is in theunmated configuration and is therefore preloaded; such preloading mayprovide an enhanced restoring force in the wire, leading to a largermating force, which in turn may provide a more robust and/or reliablecontact. Furthermore, as described above the high elastic limit andassociated deformability of the superelastic wire 806 may enable thewire to deform to conform to blade 804. The mating connectors may beconfigured such that the tip of blade 804 does not extend into thereceptacle beyond wire 806. As a result, wire 806 will be in contactwith blade 804 at least at the end of the blade 804 when mated. As aresult of this configuration, the stub length (the length of the portionof the blade which extends beyond the contact point) is reduced comparedto conventional connector designs.

FIG. 9 depicts another illustrative embodiment of an interconnectionsystem 900, formed by two mating connectors, only portions of which areillustrated. Similar to the embodiment depicted in FIG. 8, one connectorincludes a superelastic wire 906 and a beam 908 in a housing 902 forminga receiving portion of a receptacle, adapted to receive a blade 904 froma mating connector. The illustrated configuration similarly ensurescontact at the tip of blade 904 and near the distal end of beam 908,providing low stub lengths.

In the embodiment of FIG. 9, a first end of the superelastic wire isconnected to beam 908 at a first attachment point 910. Attachment point910 may be implemented in any suitable way, such as a hole in beam 908into which wire 906 is inserted and then secured in place. Such anattachment may be achieved by soldering, by deforming the metal of beam908, or in any other suitable way. The beam 908 includes a first arm 908a and a second arm 908 b. The first arm 908 a includes a bend to form acontact point 924, and the second arm 908 b includes a second attachmentpoint 914 to connect to a second end of the superelastic wire 906.Second attachment point may similarly be formed in any suitable way,including by insertion of wire 906 into a hole in the beam. As depictedin FIG. 9, the superelastic wire 906 is preloaded (bent) to provide anenhanced contact force during mating. When the blade 904 is insertedinto the connector, the blade may contact both the contact point 924 onthe first arm 908 a and the superelastic wire 906 to form an electricalconnection with at least two contact points.

FIG. 10 depicts yet another embodiment of an interconnection system1000, similar to those depicted in FIGS. 8-9. The connector includes asuperelastic wire 1006 and a beam 1008 in a housing 1002 which isadapted to receive a connector blade 1004. A first end of thesuperelastic wire 1006 is attached to beam 1008 at a first attachmentpoint 1010. Attachment point 1010 may be formed using any of thetechniques described above for attachment points 810 or 910 or in anyother suitable way.

The beam 1008 may be formed at one end to include a tab extendingupwards from the surface of the beam. The tab may include a hole throughit. A second end of the superelastic wire 1006 attaches to the tab onthe beam at a second attachment point 1014 Attachment point 1014 may beformed in any suitable way, including using a technique as describedabove for attachment points 814 and 914.

The distal end of beam 1006 may similarly include a contact point forproviding a short stub length on beam 1006. In the illustratedembodiment, the contact point is provided by a member projecting frombeam 1008. In the embodiment illustrated, that member is a wire segment1012. Wire segment 1012 may, in some embodiments similarly be formed ofsuperelastic wire. However, in some embodiments, the member may beformed using any suitable conductive structure. During mating the wiresegment 1012 and the superelastic wire 1006 contact the blade 1004 atdifferent contact points, such that a reliable electrical connection isformed, with short stubs that provide desirable high frequencyperformance. It should be understood that in the embodiments describedwith reference to FIGS. 8-10, the strains introduced in the superelasticwires 806, 906, and 1006 during mating may exceed the elastic limit ofconventional materials, and therefore the large elastic limit ofsuperelastic materials enables such designs. It should also beunderstood that other components of the connectors may be made fromsuperelastic materials in addition to the superelastic wires. Forexample, any portion of the beams 808, 908, and 1008, the wire segment1012, the blades 804, 904, and 1004, or any other suitable portion ofthe connector may be made from superelastic materials, as the disclosureis not so limited.

Depending on the particular embodiment, a superelastic component such asa wire, pin, blade, beam, etc. may have any suitable size. For example,in certain embodiments, a superelastic wire may have a diameter of about0.125 mm, about 0.177 mm, about 0.25 mm, or between about 0.08 mm andabout 0.3 mm. However, it should be appreciated, that when thesuperelastic wire is intended to form a portion of a power contact, thewire may have a larger diameter. In some embodiments, a superelasticwire may have a length between about 2 mm to 20 mm. However it should beunderstood that other sizes and/or geometries are also possible, as thedisclosure is not so limited. In some embodiments, the wire may be evensmaller than sizes indicated herein, such as a standard size regarded asultra small. Such wires may have orders less than 0.08 mm, such as onthe order of 1 mil.

According to another aspect of the present disclosure, the incorporationof superelastic materials into separable electrical connectors mayenable miniaturization of connector designs such that the overalldensity of connections in an electrical connector may be increased. Thesignal density of a connector is herein defined as the number ofconductive elements designed to carry a signal per unit length along aparticular dimension of an electrical connector. For backplaneconnectors, that dimension is typically measured parallel to the edge ofa daughter card plugged into the backplane. In some embodiments, thesignal density of a connector may be increased by reducing acharacteristic size (e.g. cross-sectional area) of various components ofthe connectors; however, such a reduction in size may make thecomponents more susceptible to damage. For example, as thecross-sectional area of a wire used in the mating interface of aconnector is reduced, any deformation of the wire (e.g. from forcecaused by misalignment during mating) may lead to large local strainswhich may cause permanent deformation.

In some embodiments, a single wire which becomes permanently deformedmay substantially destroy an entire connector and/or require complicatedand costly repairs of an interconnection system containing the damagedconnector. However, the high elastic limit of superelastic materials mayallow for such miniaturization while significantly reducing the chanceof damage to a connector from inadvertent application of force tovarious components. In particular, the deformability of superelasticmaterials may allow for higher density connector designs which maintaina desired level of robustness.

FIG. 11A shows an illustrative embodiment of a connector 1100 with aplurality of pins 1102 supported in a housing 1104. As described above,the pins may feature a smaller cross sectional area than conventionalconnectors made from conventional materials in order to achieve a higherdensity of signal conductors. FIG. 11B depicts an embodiment in whichone of the pins 1102 b has become deformed, (e.g. due to a misappliedforce during mating). If made from a conventional material, the pin 1102b may be permanently deformed and the connector may be unusable.However, a pin 1102 b made from a superelastic material may be able toundergo the deformation depicted in FIG. 11B without yielding, andsubsequently return to the undeformed state shown in FIG. 11A.

In some embodiments, the housing of a connector may further includerelief features to reduce the extent of local deformation such that aconnector may be less susceptible to permanent deformation and damageresulting from inadvertently bent wires. A relief element may guide abent over pin through an arc that provides a larger radius of curvature,and therefore less stress, than a similar pin bent over a sharp edge ofa housing. For example, FIG. 11C is an enlarged cross-sectional view ofthe connector depicted in FIGS. 11A and 11B; as depicted in FIG. 11C,the housing 1104 includes a relief element 1106 for each pin 1102 in theconnector 1100. The relief elements 1106 are formed as tapered conicalportions in the housing 1104 at the locations where the pins 1102 exitthe housing. As illustrated by the bent pin 1102 b, the tapered portionresults in an increased radius of curvature of the pin if it isinadvertently bent, compared to a design featuring a sharp corner, andthus reduces the local strain experienced by the pin Such a reduction inlocal strain may be sufficient to prevent yielding of the pin andassociated permanent damage to the connector. For example, the taperedportion may be configured such that pins 1102 may be deformed to aminimum radius of curvature of about 1.5 times the diameter of the pins.A superelastic material may undergo such a deformation without yielding,whereas a conventional material would yield and become permanentlydeformed.

In one non-limiting example, the conductors in a connector may be pinsmade from a superelastic wire having a diameter of about 0.25 mm. Asdescribed above, the connector may be configured with the pins arrangedin a two-dimensional array. For example, a 24.6 mm by 21.5 mm array mayinclude 12 rows, with each row having 6 pairs of pins forming 72differential signal pairs; each pair may have a signal to signal spacingof about 0.65 mm. Such an arrangement may provide a connector with about13.6 signal pairs per square centimeter. It should be understood thatthe superelastic material may enable sufficient mechanical robustnessfor the 0.25 mm diameter pins such that the connector may be repeatedlymated and unmated without damaging the pins.

In contrast, a conventional connector design including conductiveelements made from conventional alloys may require larger componentsand/or additional structural features to guarantee a similarly suitabledegree of mechanical robustness. For example, conventional materials maynot be reliably used in the form of small diameter wires or pins, andtherefore are often provided as wider blades. Furthermore, larger groundconductors having stiffening ribs may also be required to protect thesignal conductors. In one example, a conventional connector withconductive elements made from conventional materials may have an overallsize which is similar to the connector described above, but the largersize of the conductors may limit the density of the connector. Forexample, the conductors may be arranged in a 24.6 mm by 22.5 mm arraywith 12 rows of 4 pairs of signal conductors, each pair having a signalto signal spacing of about 1.65 mm. Such a connector may provide asignal density of about 8.7 signal pairs per square centimeter. In thisexample, the use of superelastic conductors enables a connector with asignal density which is over 55% greater than a connector utilizingconventional materials. However, it should be understood that othersuitable sizes and/or configurations of superelastic conductors may beused which may provide larger increases in signal density.

According to another aspect of the present disclosure, in someembodiments, only a portion of a conductive element may includesuperelastic materials. For example, portions which may experience largedeformations may be made from superelastic materials, while otherportions which may not be subjected to large deformations may be madefrom conventional materials. Alternatively, in some embodiments,conductive elements made from superelastic materials may be used asspring elements to provide a desired mating force between connectorcomponents made from conventional connector materials. The inventorshave recognized and appreciated that embodiments in which only a portionof an electrical connector is made from a superelastic material may bebeneficial to provide a connector with improved electronic properties.More specifically, many superelastic materials have lower electricalconductivities than conventional materials used in electricalconnectors, and thus limiting the use of superelastic materials mayimprove the overall conductivity of a connector. Furthermore, manysuperelastic materials may be more expensive than conventional materialsfor electrical connectors; therefore, the cost of connectors may bereduced by limiting the use of superelastic materials to the portions ofthe connectors in which the mechanical properties of the superelasticmaterials may be beneficial.

Accordingly, in some embodiments, a superelastic portion may be attachedand/or coupled to a portion of a connector made from a conventionalmaterial at or near the mating interface of a connector. Depending onthe particular embodiment, the superelastic portion may be attached to aconventional material by stamping, welding, riveting, or any othersuitable process of attaching, as the disclosure is not so limited. Forexample, FIG. 12 depicts an illustrative embodiment of a portion of aconductive element 1200 including a first portion 1202 made from aconventional material, and a superelastic portion 1204. In the depictedembodiment, the superelastic portion is a wire which may deform duringmating, as described above with reference to FIGS. 2-7. The wire formsthe mating contact portion of the connector. Portion 1202 forms acontact tail, here illustrated as an eye-of-the-needle press fit contacttail. The intermediate portion may be formed of the superelasticmaterial and/or the conventional material. The first portion 1202 isstamped with tabs that may be formed into a collar 1206 around thesuperelastic portion 1204 such that the conventional material andsuperelastic material are mechanically and electrically coupled. Themechanical coupling may be achieved based on the pressure of the collaragainst the superelastic material, or may be formed using soldering,welding or other attachment techniques. In the embodiment depicted inFIG. 12, the superelastic portion 1204 includes an end portion 1208which is permanently deformed to be wider than an opening of the collar1206. Such a permanently deformed end portion may improve the mechanicaland/or electrical coupling between the conventional material and thesuperelastic material, and may help to prevent the superelastic portionfrom sliding out of the collar. However, it should be understood that insome embodiments, a permanently deformed portion may have any suitableshape and may be disposed at any suitable location along a superelasticportion, including away from an end of the superelastic portion.Moreover, it should be understood that a permanently deformed portionmay not be included in some embodiments, as the disclosure is not solimited.

FIGS. 13A and 13B depict another embodiment of a connector 1300including a contact element 1302 which includes a superelastic portion1304 forming the mating contact portion of a conductive element and asecond portion 1306. The superelastic portion 1304 is formed in theshape of a wave and is joined (e.g. welded) to a second portion 1306made from a conventional material. The superelastic portion 1304 isdisposed in a housing 1308 adapted to receive a conventional connectorblade 1310. As depicted in FIG. 13B, when a blade 1310 is inserted, thesuperelastic portion 1304 is compressed between the housing 1308 and theblade 1310 to generate the required mating force. The wave shape of thesuperelastic portion 1304 is flattened when compressed.

FIGS. 14A and 14B depict two additional embodiments of mating contactportions 1400 and 1410 of conductive elements, including a superelasticportion 1404 attached to a backing plate 1402 formed from a conventionalmaterial. In the embodiment shown in FIG. 14A, the superelastic portion1404 is connected to the backing plate by a weld 1406, while in theembodiment shown in FIG. 14B, the superelastic portion 1404 is attachedby a rivet 1408.

FIG. 14C depicts a cross-sectional side view of a portion of aninterconnection system 1430 incorporating the mating contact portion1410 of FIG. 14B in a mated configuration. Similar to the embodimentdescribed above with reference to FIG. 13B, when mated, the wave shapeof the superelastic portion 1404 is compressed and flattened to generatea contact force between a connector blade 1412 and the backing plate1402. Compared to the embodiment depicted in FIG. 12, the backing platein the embodiments depicted in FIGS. 14A-14B may provide a shorterconduction path through the superelastic material between portions madefrom conventional materials. For example, as depicted in FIG. 14C, aconduction path L is formed between the blade 1412 and the backing plate1402; the length of path L may be substantially shorter than the overalllength of the superelastic portion 1404. As described above, manysuperelastic materials have an electrical conductivity that is less thanthe conductivity of conventional materials, and therefore a shorterconduction path through the superelastic material may provide improvedelectronic performance.

It should be understood that although in the above described embodimentsa superelastic portion is attached to a portion made from a conventionalmaterial, in some embodiments, the superelastic portion may not beattached to a conventional material, as the disclosure is not solimited. For example, the superelastic portion may be provided as astandalone insert configured as a spring element to provide a desiredmating force within a connector. Furthermore, although the superelasticportion is depicted as being provided between portions made fromconventional materials (i.e. conventional connector blades), in someembodiments, a superelastic insert may be provided outside of theinterface of two connector blades, and may be configured as a simplespring element to provide a contact force between the two blades.

Composite conductive elements, including superelastic portions andconventional metals, such as phosphor bronze, may be formed in otherways. For example, segments along the length of a conductive element maybe formed of different materials. The segments may be fused by welding,brazing or in any suitable way. Segments that bend, or bend to create astress above a predetermined level may be formed of superelasticmaterials while other portions may be formed of conventional materials.

As an example of another technique that may be used to form a compositeconductive element, a superelastic member may serve as a structuralsupport for the conductive element. That support may be coated with aconductive material over all or portion of its length. For example,conductive elements are often coated with gold, and such material may beused. In contrast to conventional gold coatings that are frequentlylocalized to a contact point, the conductive coating may extend outsideof the contact region and may cover large portions of the length of theconductive element, such as greater than 25%, 35%, 45%, 55%, 65%, 75%,85%, or 95% up to 100% of the length of the conductive element, in someembodiments.

Although a simple wave shape is depicted in the above describedembodiments, other geometries also may be used. For example, FIG. 15depicts an embodiment of contact elements 1500 of connector including asuperelastic portion 1504 with an “angled wave” geometry. During mating,a conventional connector blade 1502 may contact the angled wave atmultiple contact points 1506 a and 1506 b along the superelasticportion. Depending on the particular embodiment, a wave geometry, angledwave geometry, or any other suitable geometry for generating a matingforce within a connector may be formed by any suitable method,including, but not limited to, standard stamping methods, coining, heattreatment methods, or any suitable combination of methods.

In the embodiment illustrated, the angled waves are angled relative tothe width of the contact element such that a line perpendicular to theelongated dimension of the contact element, at any point within themating region will contact at least one of the waves. For example, lineL, near the proximal end of one wave is contacting the distal end of anadjacent wave. Such a configuration facilitates mating without formingelectrical stubs. With this configuration, a tip of a mating blade willbe terminated regardless of where, over its working range, it makescontact with the wavy contact element.

According to another aspect of the present disclosure, the high elasticlimit of superelastic materials also may enable designs which provide asubstantially constant impedance between conductors in a differentialpair, and thus reduce impedance variations and reflections in theconnector and improve signal integrity. The impedance between a pair ofconductors depends both on the spacing between the conductors as well asthe dielectric constant of the material between the conductors.Therefore, to provide a constant impedance, the spacing between theconductors may be varied when the conductors transition betweenenvironments with different dielectric constants.

For example, a mating contact shaped as a receptacle may have a largerexternal dimension that a mating contact inserted into the receptacle.To maintain the same edge to edge spacing between the receptaclecontacts as exists for the mating contacts, the center to centerseparation of the receptacles may be greater than the center to centerspacing of the mating contacts outside of the receptacle. As a result,the center to center spacing of the mating contact inserted into thereceptacle needs to change when inserted in the receptacle and when not.In the example of FIGS. 2A and 2B, the mating contacts are formed ofwires 204, and the change of separation, and the need for bending ofthose wires, can be seen by a comparison of FIGS. 2A and 2B.

As another example, in one embodiment, the conductors in an electricalconnector may be separated by an air gap when in an unmatedconfiguration. In the mated configuration, the conductors may beseparated by a housing material which has a higher dielectric constantthan air. In such an embodiment, the spacing between the conductors maybe increased by deforming the conductors in order to maintain a constantimpedance. Such an embodiment may be advantageous as it may provide aconnector which may be less susceptible to the above described effectsof impedance changes which may result from incomplete mating.Specifically, if a connector is inadvertently incompletely mated, afirst portion of the conductors forming a differential pair may not befully received in the housing, and thus the conductors may be separatedby an air gap. A second portion of the conductors may be received in thehousing and be separated by the housing material (e.g. plastic) with ahigher dielectric constant than air. By increasing the spacing betweenthe conductors in the housing, the impedance of the conductors may bemaintained at a substantially constant value even in an incompletelymated configuration, and undesirable reflections and/or noise fromimpedance changes may be reduced and/or minimized. Therefore, suchembodiments may provide a larger tolerance to incomplete and/or partialmating compared to connector designs which do not include such impedancematching designs.

Importantly, in order to reduce the above described negative effectsassociated with changing impedances, the change in separation betweenconductors must occur over a small distance, resulting in relativelylarge local deformations with small radii of curvature. Suchdeformations are not possible using conventional materials withoutyielding and associated permanent deformation. However, the high elasticlimit and associated deformability of superelastic materials may enablesuch deformation to be reliably and repeatedly applied to the conductorswithout yielding.

An illustrative embodiment of a connector including the above describedimpedance matching feature is described with reference to FIGS. 2A and2B. In the unmated configuration depicted in FIG. 2A, the superelasticwires 204 have a first separation 51 which is less than a secondseparation S2 which the wires have in the mated configuration, asdepicted in FIG. 2B. Having different separations between conductiveelements that form a differential pair may be useful in tailoring theimpedance along the length of a signal path through an interconnectionsystem. This increase in separation between the conductors may offset acorresponding increase in dielectric constant between an air gap in theunmated configuration to the gap comprising a housing material (e.g.plastic) in the mated configuration, thereby providing a more uniformimpedance. Similar approaches of providing, upon mating, lateral bendingof a portion of a conductive element may aid in tailoring electricalproperties like impedance or cross talk. For example, in someembodiments, spacing between two signal conductors may be decreased, orincreased as shown in FIG. 2B.

In other embodiments, spacing between signal conductors and an adjacentshield or ground conductor may be increased or decreased. In thiscontext, lateral motion implies motion perpendicular to the insertiondirection of the connectors. Using superelastic members for portionsundergoing lateral motion, instead of conventional materials, allows awider range of lateral motion and reduces the risk of damage to theinterconnection system.

The inventors have recognized and appreciated that the shape memoryeffect discussed above may be utilized to provide electrical connectorswhich require very little or no force during the initial mating process.FIGS. 16A and 16B depict an illustrative embodiment of a portion of sucha connector 1600. For example, the illustrated portion may form part ofa signal launch to provide a connection to a printed circuit board, orit may be used in any other suitable portion of a connector. FIG. 16Ashows a partially mated configuration in which the connector portion iscooled below the transition temperature. The superelastic wires 1604 maybe trained to be substantially straight when below the transitiontemperature, such that they do not contact the side walls of thereceptacles 1602. Therefore, the superelastic wires 1604 may be insertedinto the receptacles with no, or minimal force. FIG. 16B shows theconnector in the fully mated configuration, and after the connector hasbeen warmed to a temperature above the transition temperature. Thesuperelastic wires 1604 undergo a shape change such that the wirescontact the sidewalls of receptacles 1602 at multiple contact points tocreate a suitable connection. The particular shape of the superelasticwires above the transition temperature may be controlled by suitabletraining (e.g. heat treatment) to provide a contact which achieves adesired contact force. If desired, the connector may be subsequentlyremoved by cooling the connector below the transition temperature toagain induce the phase transformation and cause the superelastic wires1604 to revert to the straight shape for facile removal. Preferably, thetransition temperature is below room temperature, or alternatively, theoperating temperature of the connector, such that the connector does notbecome inadvertently disconnected during normal operation.

The various components and/or portions of connectors described hereinmay be included in any suitable combination as a part of aninterconnection system. For example, FIG. 17 depicts one embodiment ofan electrical interconnection system 1700, illustrating an environmentin which any of the above-described embodiments may be applied. Theelectrical interconnection system 1700 includes a daughtercard connector1720 and a backplane connector 1750. Daughtercard connector 1720 isdesigned to mate with backplane connector 1750, creating electronicallyconducting paths between backplane 1760 and daughtercard 1740. Thoughnot expressly shown, interconnection system 1700 may interconnectmultiple daughter cards having similar daughter card connectors thatmate to similar backplane connections on backplane 1760.

Though FIG. 17 illustrates an interconnection system which does notnecessarily include superelastic components, conductive elementscontaining superelastic mating contact portions and/or conductivereceptacles containing superelastic portions as described above, may besubstituted for some or all of the conductive elements illustrated inFIG. 17.

Further, although various embodiments described herein include one ormore components including superelastic materials, it should beunderstood that the current disclosure is not limited in this regard.For example, in some instances, the components may include materialsthat are not technically superelastic, but may include one or morecompliant materials which are operated below their yield stress (andthus do not undergo plastic deformation). In other embodiments,non-superelastic materials may be included and may be operated abovetheir yield stresses, and therefore these components may not bere-usable.

While the present teachings have been described in conjunction withvarious embodiments and examples, it is not intended that the presentteachings be limited to such embodiments or examples. On the contrary,the present teachings encompass various alternatives, modifications, andequivalents, as will be appreciated by those of skill in the art.Accordingly, the foregoing description and drawings are by way ofexample only.

What is claimed is:
 1. An electrical connector, comprising: a pluralityof contact elements disposed in an array, each of the plurality ofcontact elements comprising a contact tail and a mating contact portion,wherein at least a portion of the contact element comprises an elongatedmember formed from superelastic material.
 2. The electrical connector ofclaim 1, wherein the at least a portion of the contact element is asuperelastic wire.
 3. The electrical connector of claim 2, wherein thediameter of the superelastic wire is between 5 and 10 mils.
 4. Theelectrical connector of claim 1, wherein the at least a portion of thecontact element is the mating contact portion.
 5. The electricalconnector of claim 4, wherein the mating contact portion is a pin. 6.The electrical connector of claim 5, wherein the contact element furthercomprises a non-superelastic portion affixed to the pin.
 7. Theelectrical connector of claim 6, wherein the non-superelastic portion isa copper alloy.
 8. The electrical connector of claim 7, wherein thecopper alloy is phosphor bronze.
 9. The electrical connector of claim 1,wherein the at least a portion of the contact element is the contacttail.
 10. The electrical connector of claim 1, further comprising: aninsulative housing, wherein the plurality of contact elements aresupported by the insulative housing.
 11. The electrical connector ofclaim 10, wherein the insulative housing comprises: a plurality ofcavities, wherein the at least a portion of each of the plurality ofcontact elements is disposed within a cavity of the plurality ofcavities.
 12. The electrical connector of claim 10, wherein theinsulative housing comprises: a surface, wherein the at least a portionof each of the plurality of contact elements extends through thesurface.
 13. The electrical connector of claim 12, wherein: the surfacecomprises relief features adjacent the contact elements.
 14. Theelectrical connector of claim 1, wherein: the superelastic material ischaracterized by a stress-strain curve having a superelastic regime; anddeformation of the superelastic material within the superelastic regimeresults in at least a partial phase transformation of the elongatedmember.
 15. The electrical connector of claim 14, wherein the phasetransformation of the superelastic material comprises a reversiblemartensitic phase transformation.
 16. The electrical connector of claim1, wherein the superelastic material is nickel titanium.
 17. Theelectrical connector of claim 1, wherein the portion of the contactelement has a first conductivity and the contact element furthercomprises a coating on the portion having a second conductivity that isgreater than the first conductivity.
 18. An electrical connector,comprising: an array of mating ends; and an array of contact tailsconnected to the array of mating ends and configured for mounting to asubstrate, wherein contact tails of the array of contact tails comprisea superelastic material.
 19. The electrical connector of claim 18,wherein: mating ends of the array of mating ends comprise a superelasticmaterial; the array of mating ends faces a first direction; and thearray of contact tails faces a second direction opposite the firstdirection.
 20. The electrical connector of claim 18, wherein: matingends of the array of mating ends comprise a superelastic material; thearray of mating ends faces a first direction; and the array of contacttails faces a second direction perpendicular to the first direction. 21.The electrical connector of claim 18, wherein the contact tails have adiameter of between 5 mils and 10 mils.
 22. The electrical connector ofclaim 18 in combination with a substrate comprising holes, wherein thecontact tails are inserted into the holes of the substrate, and whereinthe holes have a drilled diameter between 10 mils and 15 mils.
 23. Theelectrical connector of claim 18, wherein the array of contact tailscomprises: signal contact tails; and ground contact tails disposedalongside the signal contact tails.
 24. The electrical connector ofclaim 23, wherein: ones of the ground contact tails are disposed betweenadjacent pairs of the signal contact tails.
 25. A connector module,comprising: a pair of conductive elements, comprising: mating portions;contact tails; and intermediate portions connecting the mating portionsto the contact tails; and an insulative member holding the intermediateportions, wherein the mating portions and/or the contact tails comprisea superelastic material.
 26. The connector module of claim 25, furthercomprising: ground conductors alongside the pair of conductive elements,wherein the ground conductors terminate in ground contact tails.
 27. Theconnector module of claim 25, wherein the pair of conductive elements iselongated along a first direction from the contact tails to the matingportions.
 28. The connector module of claim 25, wherein the matingportions are elongated along a first direction and the contact tails areelongated along a second direction perpendicular to the first direction.29. An electrical connector comprising a plurality of connector modulesof claim 25 held in an array.